Managing services

[Rick Stevens]

Jeff Vian wrote:
> 
> 
> Rick Stevens wrote:
> 
>> Fabrício Santos wrote:
>>
>>>
>>> 1. service command.
>>>
>>> I know a service in /etc/init.d (or /etc/rc.d/init.d/) may be started 
>>> using
>>> the service command but I couldn't find any proper docs on it. No man 
>>> page
>>> available. No --help switch available. Only the following is 
>>> displayed when
>>> the command is run:
>>>
>>>    Usage: service < option > | --status-all | [ service_name [ command
>>> | --full-restart ] ]
>>>
>>> Are there any more extensive docs to this utility?
>>
>>
>>
>> "service" is _very_ similar to chkconfig.  "service" is also a pretty
>> simple shell script and is found in /sbin.  Take a look at it.
> 
> 
> Service is a script that does exactly in functionality what the command 
> line call to the init script would do.  For example,   "service network 
> start"  does the same as "/etc/init.d/network start" would do.
> 
>>
>>> 2. /etc/rcX.d
>>>
>>> Inside the rcX.d directories, there are files named K99servicename and
>>> S99servicename. I supose the K stands for Kill at reboot or halt 
>>> time, and S
>>> stands for Start at bootup time. Then the numbers are just a way of 
>>> sorting
>>> the way the services are started or stopped. Is this correct? Where 
>>> can I
>>> learn more on these matters?
>>
>>
>>
>> That is correct.  When _entering_ a run level, all of the "Sxxyyyy"
>> scripts are executed in ASCII sort order.  When _leaving_ a run level,
>> all of the "Kxxyyyy" scripts are run, again in ASCII sort order, then
>> the run level is changed and the "Sxxyyyy" scripts in the new rcx.d
>> directory are run.  And so it goes.  BTW, ASCII sort order is the
>> same as you'd get if you did "ls -l /etc/rc.d/rcx.d/S*".
>>
>> Most reasonably complete system admin manuals explain this.  You might
>> want to pick up one of the Linux-specific administration manuals
>> available from O'Reilly, Sybex, Prentiss-Hall or other publishers.
> 
> 
> 
> Not quite true.
> The Kxxxxxx scripts are run when entering the run level as are the 
> Sxxxxx scripts.

You're correct.  I had been working on a modified Solaris box and let
it taint my answer.

> The differenc is the Kxxxxx scripts make sure the service named is NOT 
> running and the Sxxxxxx scripts make sure those services are started.
> Leaving a run level does nothing from that rcX.d directory, but rather 
> uses the ones in the new runlevel entry to control what happens.

Correct.  Solaris runs through the scripts differently.

>>> 3. ln -s /etc/init.d/httpd S35httpd
>>>
>>> Is there any FC1 text based utility that may create these links
>>> automatically instead of forcing the way manually like I did?
>>
>>
>>
>> "chkconfig", "ntsysv", "redhat-config-services" would all do it.  One
>> of the lines in the /etc/rc.d/init.d version of the script controls
>> which link would be created.  Again, you want it to be "S85httpd", not
>> "S35httpd", and the line that would control how one of the above
>> utilities created the link is:
>>
>>     # chkconfig : - 85 15
>>
>> The "-" means it's not to be started by default in any run level. The
>> "85" means that the "Sxx" link should be "S85httpd", and the "15" means
>> the "Kxx" link should be "K15httpd" (start late, terminate early).
>>
>>> Thanks for your help!
>>
>>
> man chksonfig to see how to use it and control the services.  You can 
> even add new services in /etc/init.d and use chkconfig to set them up.
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- Rick Stevens, Senior Systems Engineer     rstevens at vitalstream.com -
- VitalStream, Inc.                       http://www.vitalstream.com -
-                                                                    -
-      A day for firm decisions!!!   Well, then again, maybe not!    -
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